The 'E' Type Forum

Hello, i just drove my restored e-type for the first time after a restorstion of 8 years
There is a small problem with the brakes, they brake like they should but if you press the pedal a couple times in a second or two the first time there is power assist but the second time it is getting less and the third time it is gone. If you wait for a couple of seconds there is normal power assist again.
I was thinking of the vacuum tank but there appear to be no leaks. Can a vacuum tank be faulty? It isn't leaking.
If i sit in the car a day after driving there is still vacuum for the powerbrakes, but only once. It's getting less at the second time i press the brake pedal (no engine running)
Anybody any ideas?

Power brakes?

No power assistance on an S2 etype....only a servo.

Sounds like a dodgy servo with a leaky diaphragm.... I think I've read elsewhere on here about a duff batch?

I remember a car I had as a much younger man that had a servo leak, and it. Is pretty much as you describe.

Yep, servo is what i ment. Don't judge to harsh on me, i.m dutch
I don't suspect the servo, everything on the vacuum circuit is new and also the servo and mastercylinder are new. The only parts that are old are the vacuum reservoir (i can't see what can be wrong with it, it's just a bottle i believe) and the valve close to the reservoir has been replaced with a universal plastic one. Could this be the problem?

Kind regards, Rolf

Today i found out that the little piston which opens the reaction valve on the master cylinder tends to stick now and then if somebody pushes the brake pedal. Could this make the pedal hard (no power assistance) if you press the pedal for the second time in a few seconds?

Yes, the air valve sticking could produce the symptoms you describe . Try pulling it out and lubricating it with red rubber grease . If the vacuum tank is leaking you can test this by starting the car, applying the brakes once or twice, leaving the engine running for say 2 or 3 minutes, and then shutting the engine off without touching the brake pedal . Leave the car for say 6 hours, and then, without starting the engine, see whether there is still vacuum. You test for this by pressing the pedal a few times. If vacuum is present you should hear a diminishing hiss each time the pedal is pressed, and feel it go harder until after 3 or 4 presses there is no vacuum left

Thank you, the system is leak proof. If i disconnect a hose after a week there is still vacuum in the tank.
We had the air valve of and then applied the brake several times with the white plastic pin in the mastercylinder. You could feel it coming out but not retract every time when the pedal was released.